The present invention deals with the nuclear arts. It finds particular application in conjunction with electronics used in SPECT cameras and will be described with particular reference thereto. However, it is to be appreciated that the present invention may find application in PET and other nuclear cameras and the like and is not limited to the aforementioned application.
Nuclear imaging employs a source of radioactivity to image the anatomy of a subject. Typically, a radiopharmaceutical is injected into the patient. This radiopharmaceutical contains atoms that decay at a predictable rate. Each time an atom decays, it releases a xcex3-ray. These xcex3-rays are detected, and from information such as their detected position and energy, a representation of the interior of the subject is reconstructed.
Typically, a nuclear camera has one, two, or more detector heads. Each head has a large scintillator sheet, such as doped sodium iodide, which converts incident radiation into scintillations, i.e., flashes of light. An array of photomultiplier tubes is disposed in back of the scintillator to monitor for light flashes. The output of the photomultiplier tubes and associated circuitry indicates the coordinates of each scintillation on the sodium iodide crystal and its energy. Unfortunately, there are numerous non-uniformities and inaccuracies when using a large scintillator crystal and an array of photomultiplier tubes.
This type of detector is only capable of processing one nuclear event at a time. xcex93-rays incident upon the detector temporally too close together are typically discarded, i.e., ignored. The reset time is determined in part by the afterglow of the crystals, and to a lesser extent, the processing time of the electronics.
Rather than using a single, large scintillator and photomultiplier tubes, others have proposed using an array of small scintillators, each optically coupled to a corresponding photodiode or other photoelectrical device which senses a scintillation in each individual scintillation crystal. Other types of individual solid-state detectors have also been suggested. These radiation-light-photodetection systems are again limited in speed by crystal afterglow. Moreover, energy-to-light conversion efficiency of the scintillators limits detector size, hence resolution.
The present invention provides a new and improved method and apparatus that overcomes the above referenced problems and others.
In accordance with one aspect of the present invention, a nuclear imaging apparatus is given. A source of radioactivity emits xcex3-rays that strike an array of solid state detector arrays. An array of electronics process nuclear decay event information from the detector arrays, and a reconstruction processor converts them into a human readable format.
In accordance with another aspect of the present invention, a nuclear camera is given. An array of groups of detectors detect incident radiation and send output signals in response. Signal processing circuits process the signals. First level arbiters decide which signals gain priority, and a second level arbiter orders the signals from the first level arbiters. A reconstruction processor the converts the signals to an image format.
In accordance with another aspect of the present invention, a method of nuclear imaging is given. xcex93-rays are detected that produce signals and are arbitrated upon. The signals are then reconstructed into an image representation.
In accordance with another aspect of the present invention, a logic circuit arbitrator is given. Signal generators generate signals that are selectively processed by signal processors, labeled, and sent to temporary memories where they wait for a data collection bus. A token allows the signals to be passed from the temporary memories to the data collection bus.
One of the advantages of the present invention is that it decreases the effective event processing time of the system.
Another advantage resides in a direct detection of incident radiation.
Another advantage resides in its compact size.
Another advantage is that it achieves concurrent detection of radiation events.
Yet another advantage is that excellent spatial resolution is achieved.
Still further benefits and advantages of the present invention will become apparent to those skilled in the art upon a reading and understanding of the preferred embodiments.